FROZEN SOLUTIONS. 



185 



normal bands are of only 82 units interval. (See table 109.) This may 

 be due to a change in the ionization with dilution. 



To ascertain whether the rate of cooling caused a change in the 

 spectra, a solution was suddenly plunged into liquid air and excited to 

 fluorescence. Measurements were then taken on the bands, but no 

 change in wave-lengths was observed. 



TABLE 109. Uranyl sulphate in water. Frequencies and average intervals of fluorescence bands. 



URANYL SULPHATE MIXED WITH SULPHURIC ACID. 



It has been observed that the bands of the aqueous solutions move 

 toward the violet with progressive dilution with water; hence it was 

 of considerable interest to ascertain the effect of dilution with sul- 

 phuric acid. 



The addition of one volume of acid to 40 volumes of the 1/10 normal 

 aqueous solution (table 110) produces a negligible effect, but a mixture 

 of equal volumes shifts the bands back toward the red, in fact, the 

 wave-lengths of the bands at +20 are longer than those of the normal 

 solution aqueous. This can be discovered from a comparison of the 

 wave-lengths of the 1/10 normal solutions with those of the normal 

 solutions in tables 108 and 110. The effect is not evident at low tern- 



